Union officials, elected officials, and parent advocates gathered on the steps of City Hall to decry Mayor Bloomberg’s comments comparing the union to the NRA.

Elected officials, parent advocates, and three of the four Democratic candidates for mayor lined up today to call on Mayor Bloomberg to apologize for suggesting that the teachers union is like the National Rifle Association.

On his radio show last Friday, Bloomberg characterized both the United Federation of Teachers and the NRA as groups “where the membership, if you do the polling, doesn’t agree with the leadership.”

Bloomberg had made the indirect comparison before. But coming weeks after the school shooting in Newtown, Conn., and with tensions already running high with the UFT over teacher evaluations, the analogy has drawn a swift backlash from union supporters.

At a press conference on the steps of City Hall this afternoon, several City Council members and other union supporters called on the mayor to “man up” and apologize. Among the speakers were Public Advocate Bill de Blasio, Comptroller John Liu, and former comptroller Bill Thompson — mayoral candidates who are courting the union’s endorsement.

City Council Speaker Christine Quinn, the fourth likely Democratic mayoral candidate, was not present, although she had previously criticized the mayor’s comments.

Principals union president Ernest Logan said the mayor’s characterization of the unions as not representing their members was “a personal affront.” Logan said his recent reelection proved that he has his members’ support.

“I think the mayor is out of sync with the people,” he said.

The ongoing dustup comes 10 days before the deadline Gov. Andrew Cuomo set for districts to adopt new teacher evaluation or lose state funding.

Speaking this morning at an event in the Bronx, Bloomberg said focusing on his comments was a way for the union to avoid negotiations. “What they’re trying to do is have an issue so they don’t have to face evaluations,” he said when he was asked about evaluations, lavishing praise on teachers even as he undercut the union.

But Mulgrew said the mayor’s comments are not the obstacle to negotiations. Talks could easily reopen if the city would meet the union’s demand to discuss how an evaluation system would be implemented, he said.

Bloomberg likewise said it wouldn’t take much to get him back to the table. “We’re willing to talk even when they’re running nasty ads,” Bloomberg said, referring to a television ad the UFT began airing last week that criticized the mayor.

Implications of the mayor’s comments could extend far beyond city politics, AFT President Randi Weingarten said at the press conference. She said the comments undermined Bloomberg’s credentials as an anti-gun advocate and, potentially, efforts to restrict gun ownership in the country.

“The mayor has given the NRA a way to cheapen his and our advocacy,” she said. “I can only what the NRA will do with this.”